It is well known that food such as fish and meat are sold and later served in predetermined portions (on the basis of weight and/or shape). This is the case with both the catering and the household sectors. Production of such fish and/or meat portions was previously performed by manual cutting, but various accessories and portion cutting machines have been developed in recent years. Studies have shown that manual portion cutting of fish fillets into predetermined sizes and shapes can yield a deviation in portion size of up to 10%, if no special methods are employed to increase the accuracy of manual cutting. Equipment is known which is based on either weighing or some kind of imaging. Repeated studies have shown that deviation in portion size may be around 5% when weighing, scales, or imaging devices are used to control the cutting machinery. In effect, such imprecision means a loss to the producer, since he needs to take this deviation factor into account in his agreements with buyers, and allow for overweight. In all probability, therefore, the producer receives a lower price per unit weight for the raw material input as weighed in comparison to what he would receive if he could reduce the deviation from the negotiated weight.
U.S. Pat. No. 4,557,019 describes a method and equipment for automatic control of portion cutting of fish. More specifically, the patent describes portion cutting equipment whereby images of a fish filet are recorded, and the data is used to calculate and cut the filet into pieces of predetermined size.
European patent No. 504,446 also describes a method and equipment for automatic portion cutting of fish or meat material. More specifically, the patent describes automatic portion cutting equipment whereby the fish or meat to be portioned is weighed before cutting, and that data is used to calculate and cut the material into pieces of predetermined constant weight.
U.S. Pat. No. 5,184,733 describes a method and equipment for determining the volume, form, and weight of fish transported on a conveyor belt under and past imaging equipment which records a series of images, for example of a piece of fish as it is transported on the conveyer belt. Another series of images (reflections) is recorded simultaneously. These data, along with other data, such as the speed of the belt, physical properties of the material, etc., are used to determine the weight, volume, and shape of the objects in order to control equipment for grade and sort it. For example, fish fillets are sorted into various categories.
Modern food processing demands high levels of productivity and precision. The imprecision inherent in the technology described above results in large deviations in portion size. Enhanced processing technology would lead to much better utilization of raw material and thus cost-effectiveness of processing.